Soil, in simple terms, refers to the natural, loose particles covering the earth’s bedrock resulting from the weathering of rocks. These particles include gravel, rock, sand, silt, clay, loam, and humus. In this exploration, we delve into the characteristics, properties, and constituents of four main soil types: sand, silt, clay, and loam.
Sand, a prominent construction material, comprises visible particles of rock and minerals like silicon dioxide. With a particle size ranging from 2 – 4.75mm for coarse sand to 0.075 – 0.425 mm for fine sand, its larger size enhances soil aeration and drainage. When touched, sandy soil feels grainy, contributing to its light and crumbly nature.
Silt, with a particle size between sand and clay, settles as a fertile deposit on valley floors during floods. Ranging from 0.002 to 0.06 mm, silt is non-plastic and forms a smooth mud when wet, easily moldable into various shapes. In wet conditions, silt seamlessly blends with water, forming runny puddles of mud.
Clay particles, measuring less than 0.002 mm, are the finest in soil composition. Derived from the chemical breakdown of rocks, clay forms a fine-grained cohesive soil. When wet or dry, it exhibits a sticky or gluey texture due to particles sticking together. Clay soils, comprising over 25 percent clay, have high water retention capacity and exhibit expansion when wet and shrinkage when dry.
Loam, a mixture of clay, sand, and silt, combines the benefits of these textures, promoting water retention, air circulation, drainage, and fertility. These soils are fertile, easy to work with, and offer good drainage. The composition determines if it leans towards sandy or clay loam.
The combination of particles in loam varies, resulting in classifications like sandy clay loam or silt loam. The labels “clay loam,” “silt loam,” and “sand loam” signify soils predominantly composed of those specific ingredients. Understanding these soil types aids in various applications, from construction to agriculture.